Add re_workspace_hack to avoid rebuilding dependencies

[emilk]

Problem

We have many crates.
They depend on 3rd party crates, with different combination of feature flags.
Depending on what target we build for (which binary, or test, etc) different feature flags gets enabled for those 3rd party crates. If they are not EXACTLY THE SAME as THE LAST TIME you compiled, they will be recompiled from scratch (I'm looking at you, datafusion).

The solution

Enter re_workspace_hack:

• It depends on ALL our 3rd party crates with all features we need anywhere enabled
• All our crates depend on re_workspace_hack
• We remove the dependencies on re_workspace_hack just before cargo publish

Maintaining this would be hell… except we have https://crates.io/crates/cargo-hakari

TODO

• Disable re_workspace_hack in rust_checks.py
• @rerun-bot full-check

[github-actions]

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Result	Commit	Link	Manifest
✅	7d537c3	https://rerun.io/viewer/pr/10933	+nightly +main

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[github-actions]

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Result	Commit	Link
✅	7d537c3	https://landing-i2phmbaom-rerun.vercel.app/docs

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